Gray code is a quasi-weight code. If the lowest bit of the Gray code is n=1, the absolute value of the Gray code weight is (2^n)-1, and its sign alternates between positive and negative from left to right. A typical Gray code is a single-step self-complementary code with reflection and cyclic characteristics. Its cyclic and single-step characteristics eliminate the possibility of major errors when randomly taking numbers, and its reflection and self-complementary characteristics make it very convenient to find the inverse. Gray code belongs to reliability coding and is a coding method that minimizes errors.